Mechanically scanned real-time passive millimeter-wave imaging at 94 GHz

Terahertz Heterodyne Imaging Part II: Instruments

“…The multiplier and mixer in our unit were fabricated by RPG Radiometer Physics 10 and require extensive tuning (4 tuning knobs on each component) at every frequency, but these can be replaced by broad band tunerless components from Virginia Diodes 11 . We have also util- 12 up to 350 GHz to replace the Gunn and multiplier on the source side, yielding wider swept frequency capability (30 GHz), and in principle it is possible to extend the frequency by following the BWO with a harmonic multiplier. The quality of the phase lock with the backward wave tubes is not as good above 300 GHz however, and of course their mass and size greatly reduces the portability of the transmit/receive units.…”

“…The few small ( 10 element) heterodyne arrays that have been realized in the submil-limeter rely on close packing individual single pixel waveguide receivers with non optimal fill-factors [5,6,7,8]. Several clever millimeter wave array systems have been constructed in W-band (generally centered around the 94 GHz atmospheric window) but all are fairly bulky and expensive [9,10,11,12,13]. Focal plane direct detection arrays are much easier to realize in this frequency range for the reasons stated, (no LO and simple DC output) and there are many viable designs from the late 1980's to the mid 1990's for submillimeter-wave array concepts developed largely for the radio astronomy community [14,15,16,17,18,19,].…”

“…Photo of transmit/receive heads, focusing elements and sample stage of MVNA based imaging system. 12 Insight Products, PO Box 297, Brighton, MA 02135, USA 13 OML, Inc., 300 Digital Dr. Morgan Hill, CA 95037. Fig.…”

A Study on Millimeter-Wave Imaging of Concealed Objects: Application Using Back-Projection Algorithm

“…High resolution imaging due to short wavelength usage can also be easily achieved in the MMW band. With these abilities, MMW imaging has been used in a variety of applications including target surveillance and precision target imaging for military purposes [2]; safe aircraft landing [3], highway traffic monitoring in fog [4], remote sensing for civil applications [5] and concealed threat object detection for security concerns [6]. There are also some reported examples in the non-destructive testing field where the dielectric material defects are detected with the good penetration ability of MMW signals [7,8].…”

Regularization Imaging Algorithm With Accurate G Matrix for Near-Field MMW Synthetic Aperture Imaging Radiometer

“…High resolution image can also be easily achieved by the MMW imaging system with the shorter wavelength. With these abilities, MMW imaging has been used in a variety of applications including target surveillance and precision target imaging for military purposes, safe aircraft landing, highway traffic monitoring in fog, remote sensing for civil applications and concealed threat object detection for security concerns [3][4][5].…”